Solution for rust-proofing iron and steel.



UNITED STATES PATENT orr on.

WILLIAM H. ALLEN, OF DETROIT, MICHIGAN, ASSIGNOR TO PARKER RUST-PROOF COM v PANY OF AMERICA, OF DETROIT, MICHIGAN, A CORPORATION OF MICHIGAN.

SOLUTION FOR RUST-PROOFING IRON AND STEEL.

No Drawing.

To all whom it may concern:

Be it known that I, WILLIAM H. ALLEN, a citizen of the United States, and residing at Detroit, in the county of Wayne and State of Michigan, have invented a new and oxid salt of an alkali metal (such as the chromate, dichromate, manganate or permanganate of potassium or sodium) or of an alkaline earth metal (such as chromate, dichromate, manganate, or permanganate of calcium, magnesium, barium or strontium) with phosphoric acid, which mixture may be dissolved in water. These various salts 'have much the same action in connection with phosphoric acid in the presence of articles of iron and steel. 'When the solution is raised to substantially the boiling point and artieles'of iron or steel are in-" serted, intense chemical action occurs, in; dicated by the rising of gas'bubbles. When.

available for the present purpose. .These property of oxi-.

acidic oxid salts possess the dizing ferrous iron in aci solution-into ferric iron, theacidic :oxids beingreduced to basic form and, together with other bases, enterin into combmation with the acid used, osphoric in the present case.

used as required. To produce the, solution, the chromate, dichroma/to, man anate or perma anate is mixed with thep osphoric.

acid an water in such ro portions that the one parts of so ution consist of ap-.

Specification of Letters Patent.

A stock solution is usually prepared- Patented be... 17, 1918.

Application filed June 18, 1916, Serial No. 108,928.

proximately .1265 parts of available oxygen, 50 parts of phosphoric acid and the remainder of water. When sodium dichromate is used the amounts are' Sodium dichromate .7 85 pounds Phosphoric acid (75%) 66.6 pounds Water qs. to 100.00 pounds One half pound of potassium permanganate may be substituted for the sodium dichromate in the above formula.

When this solution is to be used, it is diluted with water until about 100- c. c. neutralize 150 c. c. tenth normal potassium hydrate solution to constitute a bath which is preferably heated to about, 100 (3., into which bath the articles of 'iron and steel to be treated are introduced. The iron and steel articles are attacked by the acid mixture, the action being intense at first, but after about two hours, it practically ceases,

"an insoluble basic phosphate of iron being formed at the surface of the articles being treated. The temperature'is maintained at 100" (3., stock. solution being added from to time to keep up the strength of the at Y The articles of iron and steel are then removed from the bath, air dried, and if desired, are oiled, painted or enameled.

The dichromates and permanganates of sodium and potassium are preferred for the' reason that they are easily obtainable in large quantities in the open market, but the chromates, dichromates, mang'anates and permanganates of the other metals can used for thispurpose. a a

The proportions of the available" oxygen and acid can be changedlas desired and the -use of a stock solution omitted, but. the pro- I portions noted will be found to give satisfactory results within about the t1me specified. The complete action will require more time when lower tem eratures and weaker solutions are employe 'I claim:

" 1. A bath for rust-proofing iron and steel v consisting of a solution of a phosphoric acid and a chromate ofan alkali metal.

2.. A bath for lust-proofing ironand steel consisting of. a solution of ordinary phosphoricia'cid dichroma H. ALLEN. 

